feat: add new telemetry server (#254)

Signed-off-by: Mark Sagi-Kazar <mark.sagikazar@gmail.com>

telemetry/telemetry.go

@@ -0,0 +1,48 @@
+// Package telemetry provides telemetry information for SFTPGo, such as:
+//		- health information (for health checks)
+//		- metrics
+// 		- profiling information
+package telemetry
+
+import (
+	"fmt"
+	"net/http"
+	"time"
+
+	"github.com/go-chi/chi"
+
+	"github.com/drakkan/sftpgo/logger"
+)
+
+const (
+	logSender     = "telemetry"
+	metricsPath   = "/metrics"
+	pprofBasePath = "/debug"
+)
+
+var (
+	router *chi.Mux
+)
+
+// Conf telemetry server configuration.
+type Conf struct {
+	// The port used for serving HTTP requests. 0 disable the HTTP server. Default: 8080
+	BindPort int `json:"bind_port" mapstructure:"bind_port"`
+	// The address to listen on. A blank value means listen on all available network interfaces. Default: "127.0.0.1"
+	BindAddress string `json:"bind_address" mapstructure:"bind_address"`
+}
+
+// Initialize configures and starts the telemetry server.
+func (c Conf) Initialize(enableProfiler bool) error {
+	logger.Debug(logSender, "", "initializing telemetry server with config %+v", c)
+	initializeRouter(enableProfiler)
+	httpServer := &http.Server{
+		Addr:           fmt.Sprintf("%s:%d", c.BindAddress, c.BindPort),
+		Handler:        router,
+		ReadTimeout:    60 * time.Second,
+		WriteTimeout:   60 * time.Second,
+		IdleTimeout:    120 * time.Second,
+		MaxHeaderBytes: 1 << 16, // 64KB
+	}
+	return httpServer.ListenAndServe()
+}